Yelena Isinbayeva profited from a welcome break in the dreadful weather that has disrupted the 10th world championships in Helsinki, to set her 18th world women's pole vault record on Friday.

The event was postponed from Wednesday because of gale force winds which would have made vaulting not just hazardous but potentially dangerous.

To everyone's relief Friday evening was fine and dry after morning rain and Isinbayeva took full advantage to soar 5.01 metres for her ninth world record of the year and total prize money of $160,000.

Breaking world records has become routine for the 23-year-old Russian, who plans to better six times world champion Sergei Bubka's 35 world marks.

Conditions, though, were still difficult for the vaulters with shifting winds on a cool autumnal evening and Isinbayeva's celebrations for her first world title and the second world record of the championships were prompted by relief as much as joy.

"It was difficult to wait for two days," she said. "But today I woke up and the sun was shining.

"I set out to be the winner but the wind was very difficult."

Bubka was in the Olympic stadium on Friday to watch Isinbayeva and wished her good luck before the competition.

AMERICAN SUPREMACY

The current strength of American sprinting was underlined by further golds in the women's 200 metres and the men's 400.

Teenager Allyson Felix completed a full set of gold medals for the United States in the 100 and 200 and Olympic champion Jeremy Wariner broke 44 seconds for the first time in the 400.

The only blot on the American day was a bungled change in the men's 4x100 relay which cost their team a place in Saturday's final.

Former Olympic and world 100 champion Maurice Greene watched in disbelief as Mardy Scales and Leonard Scott botched the first change while Justin Gatlin will now not be able to add a third gold medal to his 100 and 200 titles.

"It's disappointing because I had high hopes I would go out and bring home the gold," he said. "We have been practising a lot but maybe we switched the team more than we needed to."

American high hurdler Allen Johnson, who had been hoping to win a record fifth world track title, finished third behind France's Ladji Doucoure and China's Olympic champion Liu Xiang.

Doucoure, the European indoor champion, finished last in the 2004 Athens Olympic final after hitting a barrier and stumbling across the line in eighth place.

"I cannot tell you just how long I've been dreaming of this," he said. "This victory is the result of a lot of hard work, and also a lot of support from people who had believed in me."

Russians won the day's other two titles to capture second place in the medals table behind the United States.

Sergey Kirdyapkin took an early lead in the 50 km walk, clocking a personal best of three hours 38 minutes and eight seconds on a warm morning.

In the evening session Olga Kuzenkova finally won the world women's hammer title after finishing second in the last three championships.